Single channel LPDDR4 for i.MX8

I know i.MX8 is for high-end application and DRAM bandwidth is never too big. However, I got a special request that I have to let a i.MX8M use single channel (16bit data bus) LPDDR4. My operation system will be Linux from Yocto project. Can anybody tell me where to change the kernel or u-boot code to control the chip and let the chip use single channel DRAM bus only?